Ip-usn with multiple and communication method

ABSTRACT

A router connects an Internet protocol (IP)-ubiquitous sensor network (USN) with an external network. The IP-USN is disclosed when the IP-USN includes one or more routers. An IP-USN with multiple routers includes one or more routers, and sensor nodes in the IP-USN may reliably communicate with the external network. The sensor nodes in the IP-USN may communicate with one another using the router if necessary. When one router does not operate, communication with the external network is performed by using other routers.

TECHNICAL FIELD

The present invention relates to a sensor network and more particularlyto an Internet protocol (IP)-ubiquitous sensor network (USN) withmultiple routers.

BACKGROUND ART

A sensor network is a network that includes many nodes capable ofself-computing and communicating with other nodes. Each node of thesensor network may collect information including temperature, pressureand humidity through the sensor adhered to the node, and mayself-analyze the information from the sensor by self-computing.

The sensor network may collect unprocessed results from the sensors andthe analyzed results to a few nodes through communication among thenodes. In addition, the sensor nodes may collect information at a fixedposition, or the sensor nodes may have mobility due to abrupt changes inthe environment. Therefore, the sensor network requires a sensorcollecting information and communicating with other nodes, communicationequipment, a routing protocol helping communication among the nodes, andan application analyzing the information from the sensors.

Therefore, the sensor nodes are required to be implemented with thesimplest elements possible, and thus the sensor nodes need to include alimited power supply and a storage device, and a communicationcapability that is simple and is not a burden to the nodes. In addition,the sensor nodes need to be capable of rapid topology reconfiguration,because the topology of the sensor nodes changes frequently due toenvironmental influence. In addition, when only one router is included,communication is possible only among the sensor nodes.

DISCLOSURE OF THE INVENTION Technical Problem

The present invention provides an Internet protocol (IP)-ubiquitoussensor network (USN) with multiple routers that includes one or morerouters, such that the sensor nodes communicate with one another throughthe router.

The present invention provides a communication method of an IP-USN withmultiple routers that includes one or more routers, such that the sensornodes communicate with one another through the router in addition tocommunication with an external network.

Technical Solution

Accordingly, the present invention is provided to substantially obviateone or more problems due to limitations and disadvantages of the relatedart.

In some embodiments of the present invention, an Internet protocol(IP)-ubiquitous sensor network (USN) with multiple routers includes aplurality of sensor nodes having corresponding location information andperforming corresponding functions, and one or more routers that thesensor nodes use for communication with an external network. Each of thesensor nodes designates the nearest router of the routers with respectto each of the sensor nodes as a default router, and communicates withthe external network through the external router.

Each of the sensor nodes may broadcast a router request (RREQ) messageat a fixed first frequency, and each of the routers that receive theRREQ message stores location information of the corresponding sensornodes in mapping tables, respectively, and the RREQ message may providethe locations of the corresponding sensor nodes.

The routers may broadcast router advertisement (RA) messages at a fixedsecond frequency, respectively, for updating the location informationstored in the mapping table, and the RA messages may provide thelocations of the corresponding routers.

The sensor nodes that receive the RA messages may be registered to arouter that broadcasts the RA messages received via the shortestdistance.

The RREQ message may include distance information corresponding to thedistance from a sensor node broadcasting the RREQ message to the routerreceiving the corresponding RREQ message.

The distance information included in the RREQ may increase by a unitdistance whenever the RREQ message passes through sensor nodes from thesensor node broadcasting the RREQ message to the router receiving thecorresponding RREQ message.

The router that receives the corresponding RREQ message may transmit theRREQ message to another router.

The distance information included in the RREQ may increase by a unitdistance, when the router that receives the corresponding RREQ messagetransmits the RREQ message to another router.

The router that receives the corresponding RREQ message may transmit arouter reply (RREP) message to the sensor node, when the sensor nodebroadcasting the RREQ message corresponds to a sensor node thatdesignates the router as the default router.

When one of the routers does not broadcast the RA messages at higherthan the second frequency, other routers may broadcast the RA messages,and the sensor nodes designate new default routers.

When the sensor nodes communicate with one another, the sensor nodes maycommunicate with one another through the routers when paths through therouters are shorter than paths not going through the routers.

In some embodiments of the present invention, communication method of anIP-USN with multiple routers that includes a plurality of sensor nodeshaving corresponding location information, and performs correspondingfunction and one or more IP-USN routers that the sensor nodes use forcommunication with an external network includes: broadcasting an RREQmessage at a fixed first frequency, the RREQ message providing thelocations of the corresponding sensor nodes; storing locationinformation of the sensor nodes in mapping tables of the IP-USN routersthat receive the RREQ message; broadcasting RA messages at a fixedsecond frequency for updating the location information, the RA messagesproviding the locations of the corresponding routers; designating arouter as a default router that broadcasts the RA messages received viathe shortest distance; transmitting the corresponding RREQ messagereceived by the router to another router; transmitting an RREP messageto the sensor node, when the sensor node broadcasting the RREQ messagecorresponds to a sensor node that designates the router as the defaultrouter; and communicating with the external network through the routerthat transmits the RREP message including the shortest distanceinformation, which is performed by the sensor node that broadcasts thecorresponding RREQ message.

The RREQ message may include distance information corresponding to thedistance from a sensor node broadcasting the RREQ message to the routerreceiving the corresponding RREQ message.

The distance information included in the RREQ may increase by a unitdistance whenever the RREQ message passes through sensor nodes from thesensor node broadcasting the RREQ message to the router receiving thecorresponding RREQ message.

The router that receives the corresponding RREQ message may transmit theRREQ message to another router through the external network.

The distance information included in the RREQ may increase by a unitdistance, when the RREQ message is transmitted.

The communication may further include broadcasting of the RA messages atthe fixed second frequency by the routers, respectively, to exchangemapping tables with each other.

The communication method may further include broadcasting of the RAmessages by other routers to designate new default routers to the sensornodes when one of the routers does not broadcast the RA messages athigher than the second frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will become moreapparent by describing in detail example embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1 is a diagram illustrating an Internet protocol (IP)-ubiquitoussensor network (USN) with multiple routers according to an exampleembodiment of the present invention;

FIG. 2 is a diagram illustrating sensor nodes broadcasting a routerrequest (RREQ) message providing the locations of the correspondingsensor nodes at a fixed frequency;

FIG. 3 is a diagram illustrating a router broadcasting routeradvertisement (RA) messages;

FIG. 4 is a diagram illustrating the sensor nodes registering with therouter;

FIG. 5 is a diagram illustrating a path of the RREQ message from asensor node to a router;

FIG. 6 is a diagram illustrating a router that receives the RREQ messagetransmitting the RREQ message to other routers;

FIG. 7 is a diagram illustrating a router transmitting a router reply(RREP) message;

FIG. 8 is a diagram illustrating routers broadcasting the RA messages ata fixed second frequency, and exchanging mapping tables with each other;

FIG. 9 is a diagram illustrating the IP-USN when one router does notoperate; and

FIG. 10 is a flowchart illustrating a communication method of an IP-USNwith multiple routers according to an example embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention now will be described more fullywith reference to the accompanying drawings, in which embodiments of theinvention are shown. The present invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likereference numerals refer to like elements throughout this application.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting of the invention. As usedherein, the singular forms “a,” “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes” and/or “including,” when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 is a diagram illustrating an Internet protocol (IP)-ubiquitoussensor network (USN) with multiple routers according to an exampleembodiment of the present invention.

Referring to FIG. 1, an IP-USN with multiple routers 10 includes aplurality of routers 20, 30, 40 and 50, and a plurality of sensor nodes21 to 25, 31 to 34, 41 to 45 and 51 to 54. The sensor nodes 21 to 25, 31to 34, 41 to 45 and 51 to 54 have corresponding location information,and perform corresponding functions. The sensor nodes 21 to 25, 31 to34, 41 to 45 and 51 to 54 are capable of self-computing andcommunicating with other nodes through the sensors. The sensor nodes 21to 25, 31 to 34, 41 to 45 and 51 to 54 use the routers 20, 30, 40 and 50for communicating with an external network.

The sensor nodes 21 to 25, 31 to 34, 41 to 45 and 51 to 54 designate thenearest router of the routers with respect to each of the sensor nodesas a default router and communicate with the external network throughthe external router, respectively.

The nodes 21 to 25 may designate the router 20 as the default router.The nodes 31 to 34 may designate the router 30 as the default router.The nodes 41 to 45 may designate the router 40 as the default router.The nodes 51 to 54 may designate the router 50 as the default router.The router 20 is designated as the default router by the sensor nodes 21to 25 in a region 60. The router 30 is designated as the default routerby the sensor nodes 22, 23 and 31 to 34 in a region 70. The router 40 isdesignated as the default router by the sensor nodes 33, 34 and 41 to 45in a region 80. The router 50 is designated as the default router by thesensor nodes 25, 43, 44, 45 and 51 to 53 in a region 90.

FIG. 2 is a diagram illustrating the sensor nodes broadcasting a routerrequest (RREQ) message providing the locations of the correspondingsensor nodes at a fixed frequency.

In FIG. 2, the router 30 and the nodes 31 to 34 are illustrated forconvenience of explanation. Other nodes 31, 32 and 34 broadcast the RREQmessage in addition to the node 33. The router 30 receives the RREQmessage and stores location information of the corresponding sensor node30 in a mapping table.

FIG. 3 is a diagram illustrating the router broadcasting routeradvertisement (RA) messages.

The router 30 broadcasts RA messages at a fixed frequency for updatingthe location information stored in the mapping table, and the RAmessages provides the locations of the corresponding routers.

The sensor nodes that receive the RA messages are registered to a routerthat broadcasts the RA messages received via the shortest distance ofall the RA messages. Therefore, the mapping table may have updatedinformation.

FIG. 4 is a diagram illustrating the sensor nodes registering with therouter.

In FIGS. 3 and 4, the router 30 and the nodes 31 to 34 are illustratedfor convenience of explanation; however, other routers and other sensornodes perform substantially the same functions.

FIG. 5 is a diagram illustrating a path of the RREQ message from asensor node to a router.

In FIG. 5, the RREQ message from the sensor node 33 arrives at therouter 30 via a first path 35, 31 and 36. In the first path 35, 31 and36, the RREQ message passes through one intermediate sensor node 31. TheRREQ message from the sensor node 33 arrives at the router 30 via asecond path 37, 34, 38, 31 and 39. In the second path 37, 34, 38, 31 and39, the RREQ message passes through two intermediate sensor nodes 34 and31. The RREQ message includes distance information corresponding to thedistance from a sensor node to the router. The distance informationincluded in the RREQ increases by a unit distance, for example, one unitdistance, whenever the RREQ message passes through intermediate sensornodes. In the first path 35, 31 and 36, the distance informationcorresponds to one unit distance, and in the second path 37, 34, 38, 31and 39 the distance information corresponds to two unit distances.

FIG. 6 is a diagram illustrating a router that receives the RREQ messagetransmitting the RREQ message to other routers.

Referring to FIG. 6 the router 30 receives the RREQ message from thesensor node 33, and transmits the received RREQ message to other routers20, 40 and 50. Transmission of the RREQ message among the routers may beperformed through a reliable external network. In this case, thedistance information increases by a unit distance whenever the RREQmessage passes through a router. For example, the distance informationcorresponding to the distance from the router 30 to the router 20corresponds to one unit distance, and the distance informationcorresponding to the distance from the router 30 to the router 50corresponds to two unit distances.

FIG. 7 is a diagram illustrating a router transmitting the RREP message.

The router that receives the corresponding RREQ message transmits arouter reply (RREP) message to the sensor node, when the sensor nodebroadcasting the RREQ message corresponds to a sensor node thatdesignates the router as the default router. Referring to FIG. 7, therouter 70 transmits the RREP message to the sensor node 33. The RREPmessage includes the distance information included in the RREQ message.The sensor node 33 that receives the RREP message from the router 30,communicates with an external network through the path through which theRREP message including the shortest distance information passes.

FIG. 8 is a diagram illustrating routers broadcasting the RA messages ata fixed second frequency, and exchanging mapping tables with each other.

FIG. 9 is a diagram illustrating the IP-USN when one router does notoperate.

Referring to FIGS. 8 and 9, the routers 20, 30, 40, 50 respectivelybroadcast RA messages providing their own location and exchange mappingtables with each other for exchanging information of the sensor nodesrespectively designating their own default routers.

Referring to FIG. 9, when the router 20 does not broadcast the RAmessages at higher than the fixed frequency, the router 20 is determinedto be not operating, and other routers 30, 40 and 50 broadcast the RAmessages in place of the router 20. As such, the sensor nodes thatdesignate the non-operating router 20 as the default router maydesignate other routers as a default router to communicate with anexternal network.

Referring to FIGS. 1 and 8, sensor nodes may use routers whencommunication is performed among the sensor nodes.

When the sensor node 21 that designates the router 20 as a defaultrouter communicates with the sensor node 34 that designates the router30 as a default router, a path via the sensor node 21, the router 20,the router 30, and the sensor node 34 is shorter than a path via othersensor nodes.

FIG. 10 is a flowchart illustrating a communication method of an IP-USNwith multiple routers according to an example embodiment of the presentinvention.

Referring to FIG. 10, a communication method of an IP-USN with multiplerouters includes broadcasting an RREQ message at a fixed firstfrequency, the RREQ message providing the locations of the correspondingsensor nodes (step S110), storing location information of the sensornodes in mapping tables of the IP-USN routers that receive the RREQmessage (step S120), broadcasting RA messages at a fixed secondfrequency for updating the location information, the RA messagesproviding the locations of the corresponding routers (step S130),designating a router as a default router that broadcasts the RA messagesreceived via the shortest distance (step S140), transmitting thecorresponding RREQ message received by the router to another router(step S150), transmitting an RREP message to the sensor node, when thesensor node broadcasting the RREQ message corresponds to a sensor nodethat designates the router as the default router, and communicating withthe external network through the router that transmits the RREP messageincluding the shortest distance information, which is performed by thesensor node that broadcasts the corresponding RREQ message (step S160).In addition, the communication method includes comprising broadcastingthe RA messages at the fixed second frequency by the routers,respectively, to exchange mapping tables with each other (step S170). Inaddition, the communication method includes broadcasting of the RAmessages by other routers to designate new default routers to the sensornodes when one of the routers does not broadcast the RA messages athigher than the second frequency (step S180). Detailed descriptionsabout the communication method will be omitted because the communicationmethod is already described in detail with reference to FIGS. 1 through7.

INDUSTRIAL APPLICABILITY

According to example embodiments of the present invention, reliablecommunication may be performed with an external network by using anInternet protocol (IP)-ubiquitous sensor network (USN) that includes oneor more routers, and a router may be used in communication among thesensor nodes in the IP-USN.

While the present invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theclaims.

1-20. (canceled)
 21. An Internet protocol (IP)-ubiquitous sensor network(USN), comprising: a plurality of sensor nodes having locationinformation and performing a plurality of functions; and at least onerouter that the sensor nodes use for communication with an externalnetwork, each of the sensor nodes designating a nearest router withrespect to each of the sensor nodes as a default router, andcommunicating with the external network through the router.
 22. TheIP-USN of claim 21, wherein each of the sensor nodes broadcast a routerrequest (RREQ) message at a fixed first frequency, and each router thatreceives the RREQ message stores location information of thecorresponding sensor nodes in mapping tables, the RREQ message providingthe locations of the corresponding sensor nodes.
 23. The IP-USN of claim22, wherein each router respectively broadcasts router advertisement(RA) messages at a fixed second frequency for updating the locationinformation stored in the mapping table, the RA messages providing alocation of each corresponding router.
 24. The IP-USN of claim 23,wherein the sensor nodes that receive the RA messages are registered toa router that broadcasts an RA message received via the shortestdistance.
 25. The IP-USN of claim 24, wherein the RREQ message includesdistance information corresponding to the distance from a sensor nodebroadcasting the RREQ message to a router receiving the correspondingRREQ message.
 26. The IP-USN of claim 25, wherein the distanceinformation included in the RREQ increases by a unit distance wheneverthe RREQ message passes through a sensor node from the sensor nodebroadcasting the RREQ message to the router receiving the correspondingRREQ message.
 27. The IP-USN of claim 26, including at least tworouters, wherein a router that receives the corresponding RREQ messagetransmits the RREQ message to another router.
 28. The IP-USN of claim27, wherein the router that receives the corresponding RREQ messagetransmits the RREQ message to another router through the externalnetwork.
 29. The IP-USN of claim 27, wherein the distance informationincluded in the RREQ increases by a unit distance, when the router thatreceives the corresponding RREQ message transmits the RREQ message toanother router.
 30. The IP-USN of claim 29, wherein the router thatreceives the corresponding RREQ message transmits a router reply (RREP)message to the sensor node, when the sensor node broadcasting the RREQmessage corresponds to a sensor node that designates the router as thedefault router.
 31. The IP-USN of claim 23, including at least tworouters, wherein the routers respectively broadcast the RA messages atthe fixed second frequency, and exchange mapping tables with each other.32. The IP-USN of claim 31, wherein when one of the routers does notbroadcast the RA messages at higher than the second frequency, otherrouters broadcast the RA messages, and the sensor nodes designate newdefault routers.
 33. The IP-USN of claim 23, wherein when the sensornodes communicate with one another, the sensor nodes communicate withone another through a router when a path through the router is shorterthan a path not going through the router.
 34. A communication method ofan Internet protocol (IP)-ubiquitous sensor network (USN) with multiplerouters, the IP-USN including a plurality of sensor nodes havingcorresponding location information and performing correspondingfunctions, and a plurality of IP-USN routers that the sensor nodes usefor communication with an external network, the communication methodcomprising: broadcasting a router request (RREQ) message at a fixedfirst frequency, the RREQ message providing the locations of thecorresponding sensor nodes; storing location information of the sensornodes in mapping tables of the IP-USN routers that receive the RREQmessage; broadcasting router advertisement (RA) messages at a fixedsecond frequency for updating the location information, the RA messagesproviding the locations of the corresponding routers; designating arouter that broadcasts the RA messages received via the shortestdistance as a default router; transmitting the corresponding RREQmessage received by the router to another router; transmitting a routerreply (RREP) message from a default router to a sensor node, when thesensor node broadcasting the RREQ message corresponds to a sensor nodethat designates the router as the default router; and communicatingbetween the external network and the sensor node that broadcasts thecorresponding RREQ message through the router that transmits the RREPmessage including the shortest distance information.
 35. Thecommunication method of claim 34, wherein the RREQ message includesdistance information corresponding to the distance from a sensor nodebroadcasting the RREQ message to the router receiving the correspondingRREQ message.
 36. The communication method of claim 35, wherein thedistance information included in the RREQ increases by a unit distancewhenever the RREQ message passes through a sensor node from the sensornode broadcasting the RREQ message to the router receiving thecorresponding RREQ message.
 37. The communication method of claim 34,wherein the router that receives the corresponding RREQ messagetransmits the RREQ message to another router through the externalnetwork.
 38. The communication method of claim 37, wherein the distanceinformation included in the RREQ increases by a unit distance, when theRREQ message is transmitted.
 39. The communication method of claim 34,further comprising broadcasting the RA messages at the fixed secondfrequency by the routers, to exchange mapping tables between therouters.
 40. The communication method of claim 39, includingbroadcasting the RA messages by other routers to designate new defaultrouters to the sensor nodes when one of the routers does not broadcastthe RA messages at higher than the second frequency.